Selenium

Selenium (Se) is an essential nutrient which plays a key antioxidant/catalytic role in animal and human physiology through its incorporation into enzymes involved in defense against oxidative stress, regulation of redox status and metabolic modulation of thyroid hormones activities [1-4]. Se is required in particular for reproductive and immune functions and its involvement has been shown in metabolic syndrome as well as in aging [5,6]. In addition, Se deficiency can occur in people dependent on food grown from Se-deficient soil, as well as in people with severely compromised intestinal function, or those undergoing total parenteral nutrition. In this context, Se supplementation - either alone or in combination - is essential for the treatment or the prophylaxis of deficiencies, and there is a growing interest for health nutrition and clinical indications [7,8]. The European Food Safety Authority (EFSA) has recently concluded [9,10] that a cause and effect relationship has been established between dietary intake of selenium and various health benefits in the general population, i.e., that selenium contributes to

the protection of cell constituents from oxidative damage,

the normal function of the immune system,

normal thyroid function,

normal spermatogenesis function,

the maintenance of normal hair

and the maintenance of normal nails

Se is present in the food chain in two forms, mineral and organic, in which sodium selenate/selenite and L-selenomethionine (SeMet) are the major representative compounds, respectively. In higher animals and humans, Se intake occurs mainly through SeMet. Moreover, this selenoorganic compound is characterized by better bioavailability and lower toxicity than inorganic sources of Se [11].

Based on a new concept of SeMet precursor, we have designed Se-containing molecules which are novel organic compounds [12]. The basic structure NutraSelen® (THD-177), i.e., D,L-2-hydroxy-4-(methylseleno)butanoic acid (HMSeBA), has been developed as Se source for animal nutrition and it has been shown that NutraSelen® is rapidly converted into SeMet in animals and is an effective source of Se, with a safety and bioavailability comparable to that of SeMet [13-16].